1. Field of the Invention
The present invention relates to an aromatic liquid-crystalline polyester solution composition, a less anisotropic film obtained by casting said composition and a process for producing said film.
2. Description of Related Art
Since aromatic liquid-crystalline polyesters show an excellent high-frequency performance and a low hygroscopicity, they are expected to be substrate materials for electronics. Conventionally known aromatic liquid-crystalline polyester films obtained by extrusion molding, however, have a problem that they have weak mechanical properties in the transverse direction (TD) as compared to the machine direction (MD) (flow direction), i.e., have a large anisotropy, because the liquid-crystalline polyesters have a property that they are remarkably oriented in the extruding direction.
As methods for obtaining an aromatic liquid-crystalline polyester film, for example, methods have been known in which a solution composition is prepared by dissolving an aromatic liquid-crystalline polyester in trifluoroacetic acid (JP-A 62-64832), or tetrafluorophenol (JP-AB-281817), said solution composition is cast, and the solvent is evaporated from the cast product to give an aromatic liquid-crystalline polyester film. However, these solvents have problems that they have a strong corrosive property and the like and are not necessarily easy to handle.
The purpose of the invention is to provide an aromatic liquid-crystalline polyester solution composition using a solvent that is easy to handle, a less anisotropic film obtained by casting said composition and a process for producing said film.
As the result of extensive studies for an aromatic liquid-crystalline polyester solution composition having no such problems, the present inventors have found that a less anisotropic aromatic liquid-crystalline polyester film can be produced, from an aromatic liquid-crystalline polyester solution composition in which a specific amount of an aromatic liquid-crystalline polyester is dissolved in a solvent containing a specific chlorine-substituted phenol compound, by casting said solution composition and then removing the solvent.